This invention relates to a pivotal support mechanism for a fluid actuated cylinder, and more specifically to such a mechanism including means for the delivery and discharge of fluid to and from the cylinder. The invention has particular utility in conjunction with the implement actuating cylinders of construction and industrial vehicles such as the pair of blade lift cylinders of a bulldozer, but with no unnecessary limitations thereto being intended.
The pair of opposed fluid chambers in each pivoted lift cylinder of a bulldozer, for example, have usually been communicated with a pump by means of flexible conduits such as rubber hoses extending through the power plant enclosure of the vehicle. The use of such flexible conduits is disadvantageous in that they prevent the complete enclosure of the power plant. Further, such exposed flexible conduits are cumbersome and are subject to the possibility of getting hurt by the branches of trees or the like during operation of the vehicle.
A partial solution to these problems is found in Japanese Utility Model Application No. 48-15738 filed on Feb. 7, 1973 by the assignee of the instant application and laid open to public inspection on Oct. 2, 1974 (Laying-open Publication No. 49-115593). According to this prior application, each lift cylinder is fixedly mounted on a trunnion rotatably received in a stationary sleeve, and the flexible conduits are replaced by fluid passages formed in the trunnion and sleeve (as shown in FIGS. 1 and 2 of the drawings attached hereto).
This prior art device has proved to have its own drawbacks, however, in connection with the means employed for bearing the axial thrust of each trunnion. The metal particles produced frictionally by the thrust bearing surfaces cause premature damage or wear of other sliding parts located adjacently, and the entire device is in need of replacement upon wear-out of the thrust bearing surfaces, as will be later explained in further detail.